JP3200811B2 - Manufacturing method and apparatus for civil engineering materials using coal ash as a main raw material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to coal ash discharged from pulverized coal-fired boilers and the like, to which appropriate amounts of lime (slaked lime and / or quick lime) and gypsum are added, kneaded with water, molded, cured and solidified. The present invention relates to a method and an apparatus for manufacturing civil engineering materials such as roadbed materials and landfill materials by stabilizing the materials.

[0002]

2. Description of the Related Art Coal ash (fly ash) discharged from a pulverized coal-fired boiler or the like is about 50% as a raw material for cement or the like.
Has been recycled and the rest has been landfilled as waste. On the other hand, demand for coal as fuel is increasing, and the amount of ash is increasing due to the construction and expansion of coal-fired power plants. In Japan, where the advanced utilization of the land is progressing, it will become increasingly difficult to secure ash dumps in the future, and ash disposal costs are expected to rise. There is a demand for the development of technology for effective and effective utilization.

Conventionally, as a method for producing a solidified body (hardened body) using coal ash as a main raw material, for example, Japanese Patent Publication No. Sho 64-14
As described in Japanese Patent Publication No. 17, coal ash 60 to 85
Water and 10 to 25% by weight of slaked lime, and 8 to 25% by weight of gypsum are added to water and kneaded. The kneaded product is molded using a mold or a molding container. ,
There is known a curing treatment method for the molded body with normal pressure steam at 80 to 100 ° C.

Japanese Patent Application Laid-Open No. Hei 8-59311 discloses that
The amount of limestone as a desulfurizing agent supplied to the coal-fired fluidized bed boiler is adjusted according to the amount of ash in coal and / or the amount of sulfur in coal so that the amount of quicklime in combustion ash becomes 10 to 30 wt%. A method for producing a solidified body from a fluidized bed combustion ash, which is obtained by kneading a combustion ash having adjusted components with water, forming a kneaded product, and curing the mixture, is described.

[0005]

The above-mentioned Japanese Patent Publication No. 64-1
No. 417 discloses a method of adding a certain amount of slaked lime and gypsum to coal ash from a pulverized coal-fired boiler irrespective of its properties. In this method, additives (slaked lime and gypsum) are added depending on the ash composition. ) Is unnecessarily consumed to increase the cost, and conversely, the solidified material has a small amount of the additive and is insufficient in strength. Further, the method described in the above-mentioned Japanese Patent Application Laid-Open No. 8-59311 is to produce a granular solidified material from coal ash from a coal-fired fluidized bed boiler and use it as a roadbed material. The composition of the ash is up to you, and the strength of the solidified body cannot be controlled. Depending on the ash composition, a large number of defective products will be produced.

[0006] The present invention has been made in view of the above points, and an object of the present invention is to minimize the amount of additive by adding an appropriate amount of additive (lime and gypsum) according to the composition of coal ash. By expressing the strength required for the solidified body in an amount, the solidified body strength can be controlled, and therefore, it is possible to cope with various types of coal ash, and
The cost of solidification can be reduced, and safety can be ensured because harmful heavy metals are fixed to hydrates. As a result, a large amount of coal ash from pulverized coal-fired boilers can be effectively used. It is an object of the present invention to provide a method and an apparatus for producing civil engineering materials using coal ash as a main raw material.

[0007]

Means for Solving the Problems To achieve the above object, the present invention relates to a method for producing a civil engineering material using coal ash as a main raw material, wherein the coal ash has a CaO / (SiO ₂ + Al ₂ O ₃ ) weight ratio. Hydrate reaction proceeds sufficiently, and SiO ₂ and Al ₂
Lime (slaked lime and / or quick lime) is added to adjust the mixture so that the amount becomes 0.06 to 0.2, which is a range that does not cause O ₃ deficiency, and the adjusted mixture has a sufficient hydration reaction.
Gypsum having a weight of 0.2 to 1.0 times, preferably 0.25 to 0.75 times the lime converted to quick lime in a range where unreacted gypsum does not remain. In addition, a gypsum adjustment mixture was added, and at the same time, kneading water was added to the gypsum adjustment mixture and kneaded, and then the kneaded product was molded.
After curing at 55 ° C, steam curing to minimize the amount of additive
It is configured to obtain a solid material of high strength in an amount (Fig. 1
To FIG. 7). When using hydrated lime as the lime (Ca (OH) _2), in terms of Ca (OH) ₂ in the lime (CaO), CaO / (SiO 2 + Al 2 O 3) weight ratio is 0.06 to 0.2 Slaked lime is added so as to be within the range. If this value is less than 0.06, the hydration reaction does not proceed sufficiently, the strength of the solidified body decreases, and the material does not become a good quality civil engineering material. As the cost increases, SiO ₂ and Al ₂ O ₃ become deficient, the strength of the solidified body decreases, and it does not become a good quality civil engineering material. The order of mixing the coal ash, lime, gypsum, and water is not limited, and it is only necessary that these components are finally kneaded.

[0008] The amount of gypsum added is 0.2 to 1.0 times, preferably 0.25 to 1.0 times the weight ratio of quick lime added to coal ash.
It is 0.75 times. In addition, when adding slaked lime, the value converted into quick lime is used as a reference. When the amount of added gypsum is less than the lower limit, the hydration reaction does not proceed sufficiently, and the strength of the solidified body is reduced.On the other hand, when the amount exceeds the upper limit, the cost of the additive increases and unreacted gypsum is removed. It remains and the strength of the solidified body decreases. Further, industrial water or seawater is used as the kneading water, and 20 to 100 parts by weight of the gypsum mixture is used.
50% by weight are added. In this case, it is preferable to use warm water of 30 to 60 ° C. When hot water is used, the strength and stability of the solidified body are improved, and there is an advantage that stable quality of the solidified body can be ensured even in winter and cold regions. When seawater is used, there is an advantage that the strength of the solidified body is further increased.

At the time of molding, it is formed into a predetermined shape by cast molding, pressure molding or tamping molding, and then cured at room temperature to 55 ° C. for 5 to 24 hours.
Cure under saturated steam at 8 ° C for 10 to 24 hours. The upper limit of 55 ° C. in “normal temperature to 55 ° C.” is a value in consideration of a case where a kneaded product or molded product having low strength does not crack due to expansion due to a rapid hydration reaction. Room temperature to 55 ° C
In the curing treatment in the above, the harmful heavy metal is fixed by the hydration reaction product, and the landfill determination standard can be satisfied.
Furthermore, by performing the steam curing treatment, the hydration reaction proceeds further, free lime is eliminated, and harmful heavy metals are more fixed, so that the soil environmental standards can be satisfied. The cured solidified product is crushed to be a granular solidified product having a particle size distribution of 40 mm or less, specifically 0.05 to 40 mm, and is effectively used as a civil engineering material such as a roadbed material and a landfill material.

The amount of lime and gypsum added to the coal ash is determined by the ash composition of the coal burned in the boiler, for example, the ash content Ca
O / (SiO ₂ + Al ₂ O ₃ ) weight ratio may be controlled, or coal ash may be collected under a hopper such as a hopper of an electric dust collector or a relay hopper or in an air flow conveying process, and the coal ash may be collected. CaO / (SiO ₂ + Al) by fluorescent X-ray
₂ O ₃₎ performs a measurement of the weight ratio, configured to control the amount of lime and gypsum based on measured values. In addition, as gypsum, using gypsum obtained from a flue gas desulfurization device, crushing this gypsum together with part of coal ash or part of lime,
It is preferable to add a material having a brane specific surface area of 2500 cm ² / g or more to coal ash (see FIGS. 4 to 7).
Of course, it is also possible to carry gypsum from outside the system and use it. In some cases, lime is used by calcining at least one of limestone and shell to form quicklime, and pulverizing the quicklime to have a Blaine specific surface area of 2500 cm ² / g or more (see FIGS. 6 and 7). . Here, the Blaine specific surface area is a value measured using a Blaine air permeation apparatus described in JIS R 5201 (physical test method for cement) and is an index indicating the fineness of particles. Plain or lime with a specific surface area of 2,500 cm ² / g
If it is less than 1, the hydration reactivity is not good, and the compressive strength of the obtained treated product (solidified product) is not sufficient, and the possibility of elution of heavy metals occurs. As the Blaine specific surface area increases, the hydration reactivity increases, and the compressive strength of the solidified body increases, but it is economically disadvantageous. Therefore, the upper limit of the brane specific surface area is not limited, but is practically 1
It is preferable that the upper limit is set to 0.000 cm ² / g.

[0011] The present invention relates to an apparatus for producing civil engineering materials using coal ash as a main material, comprising: a dust collector for introducing exhaust gas from a coal-fired boiler to collect coal ash contained in the exhaust gas; A kneader for introducing kneading and kneading with lime, gypsum and water, a molding machine for molding the kneaded material from the kneading machine, and a curing device for curing the molded product from the molding machine, a hopper, or coal ash collected by the pneumatic conveying process _{CaO / (SiO 2 + Al 2} O 3) ratio by weight of the measurement
The quality control device that performs provided, so as to be able to control the amount of lime and gypsum to be added to the coal ash by the quality control apparatus, and the quality control device and lime feeder and gypsum feeder is interlocked connected And a solidified material comprising a coal ash-lime-gypsum-based mixture is obtained (see FIGS. 1, 4 and 6).

[0012] Further, the present invention provides an apparatus for producing civil engineering materials, comprising: a dust collector for introducing exhaust gas from a coal-fired boiler to collect coal ash contained in the exhaust gas; and a lime and gypsum for introducing the collected coal ash to collect ash. And a kneading machine for kneading with water, a molding machine for molding the kneaded material from the kneading machine, and a curing device for curing the molded product from the molding machine. A quality control device for calculating the CaO / (SiO ₂ + Al ₂ O ₃ ) weight ratio from the ash composition of the coal type of coal and determining the amount of lime and gypsum added to the coal ash is provided. In order to control the amount of lime and gypsum to be added, the quality control device and the lime feeder and the gypsum feeder are connected in conjunction with each other so as to obtain a solidified body composed of a coal ash-lime-gypsum-based mixture. What you did Is set to characters (3, 5, see FIG. 7). In these civil engineering material production devices, it is preferable to provide a crusher for crushing the cured organisms downstream of the curing device, so as to obtain a particulate solidified body composed of a coal ash-lime-gypsum mixture. .

[0013] The pulverized coal-fired boiler ash alone does not become a high-strength solidified substance even when water is added, and most of the ash is discarded, and its effective use in large quantities is mostly performed because its properties are not stable. Absent. However, coal ash has soluble SiO ₂ , Al
_The addition of lime or gypsum promotes the pozzolanic reaction because it contains a large amount of ₂ O ₃ , and forms an insoluble CSH (calcium silicate hydrate) gel or ettringite to form a high-strength solidified product. Becomes In addition, heavy metals in the ash are taken into ettringite and C—S—H and are chemically stabilized. In this way, coal ash is solidified and stabilized,
It is intended to be used effectively in large quantities by using civil engineering materials such as landfill materials. Further, by adding appropriate amounts of lime and gypsum according to each ash composition, the required strength is developed with the minimum amount of lime and gypsum added. Assuming that the target uniaxial compressive strength is 100 kg / cm ² , the added amount of lime is 2 to 9% for slaked lime and the added amount of gypsum is 1 to 6%. As described above, by controlling the amounts of lime and gypsum added, the strength of the solidified body can be controlled, and it is possible to easily cope with various types of coal ash.

In order to add lime and gypsum in appropriate amounts,
Determine the amount of lime and gypsum to be added based on the ash composition of the coal to be burned, or collect the coal ash under a hopper or from a pneumatic conveying pipe, and analyze Ca, Al, Si by manual analysis or online X-ray fluorescence. The amount of lime and the amount of gypsum added are determined according to the analysis value . Cement is also considered as a lime-based additive, but the amount of additive (cement) is 2 to 2.5 times that of slaked lime in order to achieve the same strength with cement addition. Since the cost of the additive material is 1/2, the cost of the additive material is almost the same. However, considering the ash weight basis, the use of slaked lime or quick lime can reduce the production cost of the solidified body.

Further, as a lime source, a sintering furnace (fluidized bed furnace, shaft furnace, etc.) for sintering limestone and shells is provided in the civil engineering material production apparatus of the present invention, and limestone and shells are sintered to quicklime. In addition, the cost of the additive can be further reduced. At this time, if waste oil, sludge, and the like discharged from the power plant are used as a part of the fuel for firing, not only the firing cost can be further reduced, but also the zero emission of the power plant can be contributed. Further, as described above, ettringite (3CaO.Al ₂ O ₃ .3)
Since a large amount of hydration products such as CaSO ₄ .32H ₂ O) are generated and harmful heavy metals are fixed to the hydrate, safety standards defined by environmental standards can be ensured.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments and can be implemented with appropriate modifications. FIG. 1 shows an apparatus for producing civil engineering materials using coal ash as a main raw material according to a first embodiment of the present invention, and FIG. 2 shows a solidified body production plant (solidified body production apparatus) in FIG. 1 and 2, coal (for example, pulverized coal) is supplied to a coal combustion device such as a boiler (for example, pulverized coal-fired boiler) 10 and burns, and combustion exhaust gas from the boiler is collected by a dust collector, for example, an electric dust collector ( The coal ash (fly ash) introduced into the EP 12 and contained in the exhaust gas is collected. The exhaust gas from which dust has been removed is introduced into a desulfurization device 14 such as a wet desulfurization device using a limestone slurry or the like as an absorbing liquid to remove sulfur oxides and the like in the exhaust gas. The removed sulfur oxides and the like are collected as gypsum and temporarily stored in the gypsum hopper 16. The gypsum in the gypsum hopper 16 is supplied to the solidified body manufacturing plant 20 by the gypsum supply machine 18.

On the other hand, part of the collected coal ash is sampled by the quality control device 22, transported to the coal ash hopper 24 (for example, by airflow), and temporarily stored. The coal ash from the coal ash hopper 24 is supplied to the solidified body production plant 20 by a coal ash supply device 26. Reference numeral 28 denotes a lime hopper for temporarily storing slaked lime or quick lime. The lime in the lime hopper 28 is supplied to the solidified body production plant 20 by a lime supply device 30. At the same time, kneading water is supplied to the solidified body manufacturing plant 20. The quality control device 22 includes a coal ash feeder (cutting device) 2 under a coal ash hopper 24.
6. Lime feeder (cutting device) 3 below lime hopper 28
Gypsum feeder (cutting device) below the gypsum hopper 16 and 0
The control unit 18 is configured to supply a predetermined amount to the solidified body manufacturing plant 20 by controlling the same. These feeders 18, 26, 30 include table feeders,
A screw feeder, a rotary feeder, or the like is used.

As shown in FIG. 2, the solidified body production plant 20 includes a kneader 32, a molding machine 34, a curing device 36, and a crusher 38. Examples of the kneading machine 32 include, in addition to models capable of stirring and granulating, such as a backflow high-speed kneading machine (Erich mixer), a Henschel mixer, a horizontal axis kneading machine, and a vibrating kneading machine (vibromixer), a vertical axis high-speed kneading machine. A kneader (such as a pin mixer) is suitable. As the molding machine 34, a high-pressure type such as a briquette machine, an extrusion type, a low-pressure type such as a block machine is suitable. Also,
The curing device 36 is provided at a normal temperature or a temperature near normal temperature (normal temperature to 55
℃), and a room temperature curing treatment section for curing at 60-98 ° C
A steam curing section for curing in a saturated steam atmosphere. As the curing device 36, a type in which a rack on which the solidified body is placed is sequentially moved to an outlet to perform a curing process, a type in which a curing process is performed while sequentially moving downward while being transported by a conveyor, and a stirring blade joined to the vertical axis A type in which curing is performed while sequentially moving downward with stirring can be applied. Further, as the crusher 38, an impact type such as a hammer mill, an impeller breaker, and an impact crusher is suitable.

The quality control device 22 measures the CaO / (SiO ₂ + Al ₂ O ₃ ) weight ratio of the sampled coal ash.
The amount of lime added was controlled so that the CaO / (SiO ₂ + Al ₂ O ₃ ) weight ratio was 0.06 to 0.2, and the amount of gypsum added was 0.2% of lime converted to quick lime. ~ 1.
The gypsum addition amount is controlled to be 0 times.

In the civil engineering material manufacturing apparatus constructed as described above, coal ash is collected under a hopper such as a hopper of an electric dust collector, a relay hopper, or in an air flow conveying process, and the coal ash Ca is collected.
The O / (SiO ₂ + Al ₂ O ₃ ) weight ratio is measured, and based on the measured value, the CaO / (SiO ₂ + Al ₂ O ₃ ) weight ratio becomes a predetermined value in the range of 0.06 to 0.2. So that the amount of gypsum becomes a predetermined value in the range of 0.2 to 1.0 times the lime converted to quick lime.
Is controlled to adjust the amount of coal ash, the amount of lime and the amount of gypsum supplied to the kneading machine 32. At the same time, the kneader 32 is 20 to 50% by weight based on 100 parts by weight of the coal ash / lime / gypsum mixture.
Add water and knead. Next, after the kneaded material is formed into a predetermined shape (for example, almond shape, column shape, block shape, etc.) by the molding machine 34, the formed material is cured at room temperature to 5 ° C. by the curing device 36.
Cured at 5 ° C for 5 to 24 hours, and then 60-98
Cured under saturated steam at 10 ° C for 10 to 24 hours. And
The cultivated organism is crushed by the crusher 38 to an irregular 40 mm or less (0.05 to
40 mm). By the crushing process, the modified CBR of the crushed product (granular material) becomes 80% or more, and the roadbed material,
It can be effectively used as civil engineering material such as landfill material. Here, the modified CBR is an index indicating the strength of a granular material used as a civil engineering material such as a roadbed material. The larger the larger, the better the strength is, and the JIS A 1211 (subgrade soil bearing capacity ratio (CBR)) Test method)
It refers to a water immersion CBR corresponding to a required degree of compaction with respect to the maximum dry density when each layer is compacted 92 times in three layers.

FIG. 3 shows an apparatus for manufacturing civil engineering materials according to a second embodiment of the present invention. This embodiment is the first embodiment.
CaO / (SiO ₂ + Al ₂ O ₃ ) of coal ash burned in a boiler instead of the quality control device 22 in the form
The lime addition amount and the gypsum addition amount to be added to the coal ash are determined from the weight ratio, and a quality control device 22a for controlling the addition amount is provided. Since the composition of the combustion ash is almost constant depending on the type of coal, this ash composition or CaO / (SiO ₂
+ Al ₂ O ₃ ) The weight ratio is input to the quality control device 22a,
The CaO / (SiO ₂ + Al ₂ O ₃ ) weight ratio of the coal ash becomes a predetermined value in the range of 0.06 to 0.2, and
The supply valves 26, 30, and 18 are controlled so that the amount of gypsum becomes a predetermined value in the range of 0.2 to 1.0 times the lime converted to quick lime, and the amount of coal ash supplied to the kneader 32, Adjust the amount and gypsum amount. Other configurations and operations are the same as those in the first embodiment.

FIG. 4 shows an apparatus for manufacturing civil engineering materials according to a third embodiment of the present invention. In the present embodiment, a mill 40 for crushing flue gas desulfurization gypsum is additionally provided. That is, since the flue gas desulfurization gypsum is in a wet state, the handling property is poor, and the crystal is large, about twice the amount of coal ash is removed from the coal ash hopper 24 by the coal ash feeder 42 into the mill 40.
And mixed with gypsum and crushed. As the mill 40, a vibration mill, a ball mill, a roller mill, or the like is used. Instead of supplying coal ash to the mill 40, lime from the lime hopper 28 is supplied to the mill 40 via the lime feeder 44.
May be supplied. The mixed and pulverized product of gypsum and coal ash or the mixed and pulverized product of gypsum and lime is temporarily stored in the gypsum mixture hopper 46 and then supplied to the solidified body production plant 20 by the gypsum mixture supply device 48. The quality control device 22
CaO / (SiO ₂ + Al) of sampled coal ash
₂ O ₃ ) The weight ratio was measured, and CaO /
(SiO ₂ + Al ₂ O ₃ ) The weight ratio is set to a predetermined value in the range of 0.06 to 0.2, and the amount of gypsum is in the range of 0.2 to 1.0 times the lime converted to quick lime. The feeder 26, 30, 42, 48 or the feeder 2 is set to a predetermined value.
By controlling 6, 30, 44 and 48, the amounts of coal ash, lime and gypsum supplied to the kneader 32 are adjusted. Other configurations and operations are the same as those in the first embodiment.

FIG. 5 shows a civil engineering material manufacturing apparatus according to a fourth embodiment of the present invention. This embodiment is a third embodiment.
CaO / (SiO ₂ + Al ₂ O ₃ ) of coal ash burned in a boiler instead of the quality control device 22 in the form
The lime addition amount and the gypsum addition amount to be added to the coal ash are determined from the weight ratio, and a quality control device 22a for controlling the addition amount is provided. Other configurations and operations are the same as those of the second and third embodiments.

FIG. 6 shows an apparatus for manufacturing civil engineering materials according to a fifth embodiment of the present invention. In the present embodiment, a sintering furnace 50 for sintering limestone and / or shells to produce quicklime is additionally provided. Generally, a coal-fired power plant is provided in an area adjacent to the sea, and a large amount of shells can be obtained from an outlet of seawater as cooling water. Therefore, the shells or limestone are converted into a firing furnace 50 (for example, a fluidized bed furnace). , Shaft furnace, etc.), and calcined to produce quicklime (CaO), which is temporarily stored in the quicklime hopper 52. Since this quicklime is in the form of particles, it needs to be supplied to the solidified body manufacturing plant 20 after being pulverized. For this reason, quicklime from the quicklime hopper 52 is milled by the quicklime feeder 54 into a mill 56 (for example, a vibration mill,
The gypsum from the gypsum hopper 16 is simultaneously supplied to the mill 56 by the gypsum feeder 18 to be pulverized, temporarily stored in the gypsum / quick lime hopper 58, and then solidified by the gypsum / quick lime feeder 60. It is supplied to the body manufacturing plant 20. The quality control device 22 calculates the CaO / (SiO ₂ + Al ₂ O ₃ ) weight ratio of the sampled coal ash.
Was measured, based on measurements, CaO / (SiO ₂ + A
l ₂ O ₃ ) The weight ratio is set to a predetermined value in a range of 0.06 to 0.2, and the amount of gypsum is set to a predetermined value in a range of 0.2 to 1.0 times lime converted to quick lime. By controlling the feeders 26, 54, 18, and 60, the amounts of coal ash, quick lime, and gypsum supplied to the kneader 32 are adjusted. In this embodiment, the case where the grinding of the quicklime and the grinding of the gypsum are performed at the same time by the mill 56 is shown. However, the grinding of the quicklime and the grinding of the gypsum may be performed separately by another mill. . In this case, as in the third embodiment, it is preferable that the gypsum is mixed with a part of the coal ash and pulverized. Other configurations and operations are the same as those in the first and third embodiments.

FIG. 7 shows a construction material manufacturing apparatus according to a sixth embodiment of the present invention. This embodiment is the fifth embodiment.
CaO / (SiO ₂ + Al ₂ O ₃ ) of coal ash burned in a boiler instead of the quality control device 22 in the form
A lime addition amount and a gypsum addition amount to be added to coal are determined from a weight ratio, and a quality control device 22a for controlling the addition amount is provided. Other configurations and operations are the same as those in the second and fifth embodiments.

[0026]

EXAMPLES Examples and comparative examples are shown below to further clarify the features of the present invention. Example 1 Plaster having 4.6 parts by weight of slaked lime and a Blaine specific surface area of 3000 cm ² / g in 100 parts by weight of coal ash A having a CaO / (SiO ₂ + Al ₂ O ₃ ) weight ratio of 0.058 shown in Table 1.
2 parts by weight, CaO / (SiO ₂ + Al ₂ O ₃ )
26 parts by weight of warm water (50 ° C.) was added to 100 parts by weight of the mixed powder having a weight ratio of 0.10, and the mixture was kneaded with a reverse-flow high-speed kneader, and the kneaded product was compacted and molded. ° C
After curing for 15 hours at 95 ° C., curing was carried out at 95 ° C. for 15 hours to produce a solid. The compressive strength of the solidified body is 115 kg / cm ²
And the amount of harmful heavy metals eluted also met the soil environmental standards.

[0027]

[Table 1]

Example 2 As shown in Table 1, 100 parts by weight of coal ash B having a CaO / (SiO ₂ + Al ₂ O ₃ ) weight ratio of 0.025, 4.0 parts by weight of quicklime and a brane specific surface area of 3000 cm ² / g. Gypsum3.
0 parts by weight, and CaO / (SiO ₂ + Al ₂ O ₃ )
Example 1 was performed using a mixed powder having a weight ratio of 0.072.
A solid was produced under the same conditions as described above. The compressive strength of the solidified body is 1
It was 00 kg / cm ² , and the harmful heavy metal elution amount also satisfied the soil environmental standard.

Example 3 Using a quality control device provided in the air ash conveying process of coal ash,
When the pH of the 10% slurry of the collected coal ash B was automatically measured, it was 10.8. Based on this value, the slaked lime supply amount and the gypsum supply amount of the civil engineering material production device were controlled. Specifically, 6 parts by weight of slaked lime is supplied to a reverse-flow high-speed kneader with respect to 85 parts by weight of coal ash, and 3 parts by weight of flue gas desulfurization gypsum is pulverized together with 15 parts by weight of coal ash in a vibration mill to have a Blaine specific surface area of 3000 cm. ² / g and gypsum mixture 1
8 parts by weight were supplied to the kneading machine, and CaO /
The (SiO ₂ + Al ₂ O ₃ ) weight ratio was set to 0.079.
To 100 parts by weight of the mixed powder, 24 parts by weight of warm water (50 ° C.) was added and kneaded, and the kneaded material was shaken at a pressure of 0.5 kg / cm ² G using a low-pressure vibration molding machine while
× 100H [mm] and then at about 40 ° C
After curing at 98 ° C. for 15 hours, a solid was produced. The solidified body had a compressive strength of 107 kg / cm ² , and the harmful heavy metal elution amount satisfied the soil environmental standard.

Example 4 The solidified product of Example 3 was crushed by an impact crusher to obtain a granular solidified product equivalent to crusher run C-40.
Modified CBR of granular solidified material is 105%, and abrasion loss is 3
5% satisfied the crushed stone roadbed material standard. The crusher run C-40 is a granular material that has been divided (crushed) by a crusher (crusher) and has a maximum particle size of 40 mm and is a material used for roadbed materials and the like.

Comparative Example 1 This comparative example is an example in which the amount of added gypsum is less than the range in the present invention. To 100 parts by weight of coal ash A shown in Table 1, 4.6 parts by weight of slaked lime and 0.5 part by weight of gypsum were added.
A solid was produced in the same manner as in Example 1. The solidified product has a compressive strength of 60 kg / cm ² and a harmful heavy metal elution amount of Cr ^6+.
Is 0.06mg / l, which is 0.05mg / l of the soil environmental standard value.
Crossed.

Comparative Example 2 This comparative example is an example in which the CaO / (SiO ₂ + Al ₂ O ₃ ) weight ratio is smaller than the range in the present invention. Table 1
, 3.0 parts by weight of slaked lime,
CaO / (SiO of mixed powder to which gypsum 2.0 parts by weight was added
₂ + Al ₂ O ₃ ) A solidified body was produced in the same manner as in Example 1 except that the weight ratio was 0.052. The compressive strength of the solidified material is 43
kg / cm ² , and the amount of harmful heavy metals eluted is 0.01 for Se.
5 mg / l exceeded the soil environmental standard of 0.01 mg / l.

[0033]

As described above, the present invention has the following effects. (1) The amount of lime added and the amount of gypsum added during the production of a solidified product using coal ash as a main raw material are determined by the CaO / (SiO ₂ +
(Al ₂ O ₃ ) By controlling the weight ratio to be a constant value and controlling the amount of gypsum to be a constant multiple of quicklime to an appropriate amount, it is possible to efficiently obtain a solidified body having a target strength. . (2) By setting the added amount of lime and the added amount of gypsum at the time of producing the solidified product to an appropriate amount (minimum amount), the cost of producing the solidified product can be minimized. Also, a relatively large amount of coal ash can be treated. (3) It is possible to cope with multi-charcoal seed ash, a solid of predetermined quality is stably obtained irrespective of the properties of coal ash, and it can be effectively used as a civil engineering material such as a roadbed material and a landfill material. (4) If the lime, fuel, etc., required for the production of solidified material are covered by the waste from the coal-fired power plant, the power plant can achieve zero emissions.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an apparatus for producing civil engineering materials using coal ash as a main raw material according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing an example of a solidified body production plant in FIG.

FIG. 3 is a schematic configuration diagram showing an apparatus for manufacturing civil engineering materials using coal ash as a main raw material according to a second embodiment of the present invention.

FIG. 4 is a schematic configuration diagram showing an apparatus for producing civil engineering materials using coal ash as a main raw material according to a third embodiment of the present invention.

FIG. 5 is a schematic configuration diagram showing an apparatus for producing civil engineering materials using coal ash as a main raw material according to a fourth embodiment of the present invention.

FIG. 6 is a schematic configuration diagram showing an apparatus for producing civil engineering materials using coal ash as a main raw material according to a fifth embodiment of the present invention.

FIG. 7 is a schematic configuration diagram showing an apparatus for producing civil engineering materials using coal ash as a main raw material according to a sixth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Boiler 12 Electric dust collector 14 Desulfurization apparatus 16 Gypsum hopper 18 Gypsum supply machine 20 Solidified body manufacturing plant 22, 22a Quality control apparatus 24 Coal ash hopper 26, 42 Coal ash supply machine 28 lime hopper 30, 44 Lime supply machine 32 Kneader 34 Molding machine 36 curing device 38 crusher 40, 56 mill 46 gypsum mixture hopper 48 gypsum mixture feeder 50 firing furnace 52 quick lime hopper 54 quick lime feeder 58 gypsum / quick lime hopper 60 gypsum / quick lime feeder

────────────────────────────────────────────────── (5) Continuation of the front page (51) Int.Cl. ⁷ Identification code FI C04B 22:14) (56) References JP-A-56-1555064 (JP, A) JP-A-48-93620 (JP, A) JP-A-57-92560 (JP, A) JP-A-9-156971 (JP, A) JP-A-9-262276 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 7/00-28/36 B09B 3/00

Claims (10)

(57) [Claims] 1. Coal ash contains CaO / (SiO ₂ + Al ₂ O)
₃₎ the weight ratio of the hydration reaction proceeds sufficiently, and SiO ₂ 及
A range that does not fine Al ₂ O ₃ and lack 0.06 to 0.
Lime is added to obtain an adjusted mixture, and the adjusted mixture is sufficiently hydrated, and
A gypsum of 0.2 to 1.0 times the weight of lime converted to quick lime, which is a range in which the gypsum of the reaction does not remain, is added to a gypsum adjustment mixture, and at the same time, kneading is performed by adding kneading water to the gypsum adjustment mixture. The kneaded product is molded, and then the molded product is brought to room temperature to
After curing at 55 ° C, steam curing to minimize the amount of additive
A method for producing a civil engineering material using coal ash as a main raw material, characterized in that a high-strength solidified body is obtained in an amount . 2. The method according to claim 1, wherein the solidified material is crushed into a granular solidified material having a particle size of 40 mm or less. 3. The method according to claim 1, wherein warm water of 30 to 60 ° C. is used as the kneading water. 4. The amount of lime and gypsum added to coal ash,
CaO / (SiO ₂ +
4. The method according to claim 1, wherein the control is based on the weight ratio of Al ₂ O ₃ ). 5. collected coal ash hopper or under pneumatic conveying process performs measurement of _{CaO / (SiO 2 + Al 2} O 3) ratio by weight of the coal ash, the addition of lime and gypsum based on the measured value A method for producing a civil engineering material using coal ash as a main raw material according to claim 1, wherein the amount is controlled. 6. A gypsum obtained from a flue gas desulfurization unit is used as the gypsum, and this gypsum is pulverized together with a part of coal ash or a part of lime to have a Blaine specific surface area of 2500 cm ² / g.
The method for producing a civil engineering material using coal ash as a main raw material according to any one of claims 1 to 5, wherein the above-mentioned components are added to coal ash. 7. The lime according to claim 1, wherein at least one of limestone and shells is calcined to form quicklime, and the quicklime is pulverized to a Blaine specific surface area of 2500 cm ² / g or more. A method for producing civil engineering materials using coal ash as a main raw material. 8. A dust collector for introducing flue gas from a coal-fired boiler and collecting coal ash contained in the flue gas, a kneader for introducing the collected coal ash and kneading it with lime, gypsum and water; In a coal ash processing apparatus provided with a molding machine for molding a kneaded product from a kneading machine and a curing device for curing the molded product from the molding machine, the CaO / CaO /
The quality control device for performing measurements of _{(SiO 2 + Al 2 O 3} ) ratio by weight is provided to be able to control the amount of lime and gypsum to be added to the coal ash by the quality control apparatus, and the quality control device An apparatus for manufacturing civil engineering materials using coal ash as a main raw material, wherein a lime feeder and a gypsum feeder are interlocked and connected to obtain a solidified body composed of a coal ash-lime-gypsum-based mixture. 9. A dust collector for introducing exhaust gas from a coal-fired boiler and collecting coal ash contained in the exhaust gas, a kneader for introducing the collected coal ash and kneading it with lime, gypsum and water; In a coal ash processing apparatus including a molding machine for molding a kneaded product from a kneading machine and a curing device for curing a molded product from the molding machine, a CaO composition based on the ash composition of a coal type of coal to be burned in the coal-fired boiler. / (SiO ₂ + Al ₂ O ₃ ) Calculate weight ratio to determine the amount of lime and gypsum added to coal ash, and control the amount of lime and gypsum added to coal ash by this quality control device The lime feeder and the gypsum feeder are linked and connected to each other so as to obtain a solidified material composed of a coal ash-lime-gypsum-based mixture. Made from soil Materials for manufacturing equipment. 10. The method according to claim 8, wherein a crusher for crushing the living organisms is provided downstream of the curing device so as to obtain a granular solidified substance composed of a coal ash-lime-gypsum mixture. Manufacturing equipment for civil engineering materials using coal ash as a main raw material.